This invention relates to tissue culture in which cells are grown in vitro in appropriate tissue culture media.
Various cell culture techniques including general laboratory instructions, cell propagation on various supports, counting of cell populations, the preparation of media reagents, etc. may be found in the Handbook of Cell and Organ Culture-Merchant, et al., Minneapolis, Burgess Publishing Company, 1964, Second Edition, and Tissue Culture (Methods and Applications) edited by P. F. Kruse, Jr. and M. F. Patterson, Jr., N.Y., Academic Press, 1973. In the commercial cultivation of cells, the cells grow as a monolayer on some sort of substrate, most commonly glass, or non-toxic plastic, in contact with tissue culture medium. Typically, the substrate may be the inner surface of a vessel containing the medium or may be the surface of small solid particles kept suspended in the medium. This latter mode of cell culture is also disclosed in "Microcarrier Culture of Vascular Endothelial Cells On Solid Plastic Beads" by P. F. Davies [Experimental Cell Research 134 (1981), pp. 367-376]. Several kinds of transformed cells will grow and divide in suspension in the tissue culture medium itself. The article "Microcarrier Cell Culture: New Methods for Research-Scale Application" by Levine, et al. [Somatic Cell Genetics, Vol. 3, No. 2, 1977, pp. 149-155] describes preparing hydrated beads of positive charge carrying dextran microspheres.
Still another method for cell and tissue culture which provides for the culture of cells at a liquid-liquid interface is described in the article by M. D. Rosenberg, "The Culture of Cells and Tissues at the Saline-Fluorocarbon Interface". In: Tissue Culture (Proceedings of the Seminar held in Baroda under the auspices of the University Grants Commission and the Maharaja Sayajirao University of Baroda, India, Jan. 21-28, 1965 edited by C. V. Ramakrishnan, Dr. W. Junk, publishers, the Hague, 1965, pp. 93-107). The cell culture system described by Rosenberg consists of a lower fluorocarbon liquid phase and an upper saline or nutrient liquid phase. The cells are grown in contact with the substantially planar interface between these two liquid phases. The use of silicone oils in place of the liquid fluorocarbons is also reported. This article by Rosenberg is incorporated by reference.
Further, it is reported in the article by N. G. Maroudas, "Chemical and Mechanical Requirements for Fibroblast Adhesion" [Nature, Vol. 244 (Aug. 10, 1973), pp. 353,354] that cells have been grown on the interface between medium and droplets of silicone oil.
The general process for growing cells on protein-coated droplets in an emulsion is described and claimed in U.S. patent application Ser. No. 443,311-Giaever and Keese, filed Nov. 23, 1982. Ser. No. 443,311 is a continuation-in-part of U.S. patent application Ser. No. 344,673-Giaever and Keese, filed Feb. 1, 1982.